Process of preparing insoluble elastic rubberlike composition



toleslatoilex courosmon- Ideh'terf Germanyr Corporation,lilewl'olrk,

amigmlrv N. Y acorperaticnofNewYork No Drawing.

rial No. 231,341. 1935 claim.

This invention relates to the production of a new synthetic substance having the properties of softness, elasticity, flexibility and stretchability. possessed by rubber, but without the deflcien I cies of rubber such as becoming hard with age and solubility in oil, benzene and similar fluid fuels. g

The new substance of this invention is adapted to the production of hose, tubing, packing, dia- 10 phragms, coatings or linings, insulation and the like where insolubility in oils and fluid fuels or organic solvents is of particular .This I substance is also insoluble in water. According to this invention the new substances ll are produced by the treatment in solution of polyacrylic acid derivatives, particularly the polyacrylic acid esters. The ethyl and methyl esters of polyacrylic acid are suitable starting materials, especially the methyl esters.

polyacrylic acid derivatives in solution with certainagents which react to form new or altered substances which have the desired properties of flexibility, elasticity and especially insolubility as in most organic solvents, even the solvents in which the polyacrylic'acid derivative is initially soluble. The methyl ester of polyacrylic acid itself possesses to a certain extent the properties desired in the final product in that it forms a so soft, flexible and elastic mass which is, however,

soluble in benzol and a number of other organic solvents, making-it of no use for the production of tubing, packing and the like in connection with the handling of solvents and fluid fuels. It

has been found that when such polyacryiic acid derivatives are treated as hereinafter disclosed this undesired solubility can be eliminated, reduced or controlled. The treatment may be carried out by means of a variety of substances which are recognized as albumin precipitants, including tanning agents, heavy metals and cer- 3m heavy metal compounds, or mixtures of .It has been found that if a solution of acrylic acid ester has added to it'flnely divided metal, metal oxide, hydroxide, salt or salt-like compounds of'metal, a reaction takes place producing a mass which is insoluble in water, benaol, benzine, alcohol, oil, or mixtures of these, and so in most common organic solvents, even including those in which the polyacrylic acid ester is soluble, such for example as acetone, acetic ether and the like.

Themetalor metalcompoundsmaybe added ss-to a solution of the polyacrylic acidderivative in The invention broadly consists in treating aitress In Germany 18;

(CI. H) v example copper, the process may be carried out 10 with an addition of pure vmetal in the'form of a powder. A relatively small amount of the added metal or metal compoundmay be suiflcientfor v producing th reaction; ranging from a small percent of the weight of the dry substance to less than one percent.

The reaction which takes place in the solution may become apparent as a coagulation which takes place immediately or after a substantial interval of time. It has been noted, however, that the readiness with which coagulation takes place depends'upon the type or the degree of purity of the polyacrylic acid derivative. In some cases the addition of metal or metal compound will not result in coagulation although a reaction has nevertheless taken place, so that the substance which is obtained upon evaporation of the solvent has the desired insclubility..

The addition we solution of polyacrylic acid ester of substances in the class recognized as albumin precipitants produces'a reaction result ing in insolubility of the flnal product. Coagulation usually takes place," but not-necessarily. For example, through the addition of tannic'acid antimony compound a substance is obtained without coagulation which is insoluble in benzol and which is otherwise as insoluble as the ester before treatment. The addition of tannic acid iron compound resultsin strong coagulation, producing a substancelikewise insoluble in benzol.

In forming the solutions of polyacrylic acid derivatives preparatory to treatment any solvent for the derivative may be used, including acetone and acetic ether (ethyl acetate).-

The following is an example using a metal salt solution and tanning agent in conjunction:

mm; 1 To 53 gr. of a 19% solution of polyacryuc acid methyl esterin acetic ether (containing 10 gr. ofthedry substance) .tbereis added 1 gr. of tannic acid and-7.5 c.c. of a filtered solution of 3 gr.

ferric acetatein 17 cc.ofwater. Thismixtur'ecoagulates strongly. yielding a light brown flexible.

substance insoluble in most organic solvents including benzol and acetic ether.

The following is an example of the use of a pure metal:

Example 2 Approximately 19 gr. of solid polyacrylic acid methyl ester is dissolved in 75 gr.of acetic ether with the addition of 3 cc. of water. When 2 gr.

of metallic copper powder is added the substance.

coagulates and becomes insoluble even in the principal solvent for acrylic acid ester, namely acetic ether. e

The substances obtained in this manner are characterized by being insoluble inwater as well as in fluid fuels (benzine, ,benzol, alcohol, and their mixtures) and in oils of all kinds. They excel previously known synthetic substances of similar type in softness and plasticity without the addition of special softening agents. Thei hre'" As illustrated by the examples given above, the

agent added to the solution of polyacrylic acid derivative may be a metal or metal compound'by itself or a mixture of metal or metal compound and tanning agents. As the amount of tanning agent is increased the amount of metal or metal compound may be decreased. A similar result may be obtained by the addition of potassium permanganate which may be added gradually in small amounts to induce coagulation.

By proper selection of the reactant and its amount there is a wide range through which the solubility of the product relative to various solvents can be altered, producing substances suitable for various uses. For example, it may be desired to produces. soi't rubberlike product insoluble in benzol and having high dielectric strength. In such case it is not'dsired to use metal and unnecessary to achieve complete insolubility in all solvents. The following example is given as illustrative:

Example 3 d of forming such coatings on fabric or the like is also contemplated, however, using agents which will result in immediate coagulation. ,l'br example, a fabric may be first coated or'impregnated with the metal, metal compound. or tanning agent, in solution if desired. and thereafter passed through a bath of the polyacrylic acid derivative in solution. The fabric will thereupon become enveloped in the coagulated mass. Still another method is to use a coagulating solution of such dilution that coagulation will take place very slowly, allowing time for coating, painting or i pregnating.

Such a dilute solution as that just mentioned may also be used for'spinning fibers, by a process similar to the cellulose spinning process, the solution being spun into a bath of water which causes coagulation.

The new substances obtained by the methods setforth may be formed into any desired shape bypressing, calenderin'g or extruding, with little or no loss of softness .or plasticity. Temperatm'es of from 50 to 803 C." have been found suitable for forming. Thus tubes, bands, ribbons, filaments and shaped articles may easily be manufactured. Those new substances which are produced by coagulation are preferably formed prior .to the complete removal ofthe solvent by evaporation while those substances which result from evaporation of an uncoagulated solution may be worked up even after the solvent has apparently been completely evaporated.

What is claimed is:

1. The method of making a substantially insoluble elastic rubberlike composition, which comprises dissolving an ester of polyacrylic acid and a monohydric aliphatic alcohol of not more than two carbon atoms in a suitable solvent, and treat- ,ing said ester while in solution with an agent comprising metallic copper in finely divided form in an amount sufllcient to produce coagulation, and separating the coagulated material from the excess solvent.

2. The method of making a substantially insoluble elastic rubberlike composition, which comprises dissolving an ester of polyacrylic acid and a monohydric aliphatic alcohol of not more than two carbon atoms in a suitable solvent, treating said ester while in solution with an agent comprising copper and a copper compound, and

separating the resulting product from the solvent.

3. The method of making a substantially insoluble elastic rubberlike composition, which comprises dissolving the methyl ester of polyacrylic acid in a suitable solvent, treating said ester while in solution with an agent comprising copper and a copper compound, and separating the resulting product from the solvent.

4. The method of making a substantially insoluble elastic rubberlike composition, which comprises dissolving an ester of polyacrylic acid and a monohydri'c aliphatic alcohol of not more than two carbon atoms in a suitable solvent, treating said ester while in solution with an agent comprisinga copper compoimd, and separating the resulting product from the solvent.

5-. The method 01 making a substantially insoluble elastic rubber-like composition, which comprises dissolving polyacrylic acid methyl ester in ethyl acetate containing a small amount of water, treating. said ester while in solution with an agent comprising finely divided metalliccopper, and separating the ooagulated material from the excess solvent.

ERNST scmmnnn. 

